Indolo[3,2,1-jk]carbazole Derivatives-Sensitized Solar Cells: Effect of π‑Bridges on the Performance of Cells

Abstract

Four organic dyes based on indolo­[3,2,1-jk]­carbazole (IC-1, IC-2, IC-3, and IC-4) with different π-bridges (benzene ring and thiophene ring) are used for dye-sensitized solar cells (DSSCs) to investigate the effect of π-bridge on their photovoltaic performance. The introduction of thiophene ring as π-bridge (the dye IC-2) greatly improves the cell performance compared to benzene ring. The increasing conjugation length of the molecules decreases the performance of DSSCs. The best performance of DSSC based on IC-2 is obtained with a <i>V</i>_oc of 0.66 V and a conversion efficiency of 3.68%. The poor performance of DSSCs based on IC-1 and IC-3 which contains only benzene ring as the π-bridge can be attributed to poor spectral coverage and higher electron charge transfer resistance as evaluated from EIS studies